This In-Btween Gripper has a large contoured grip handle and a large round suction cup with a handy lock & release lever. Just press to any plastic ruler with a smooth surface, then flip the lever to lock in place. When you need to switch to another ruler, just flip the locking lever to release. It will work on any smooth surface rulers at least 4-1/8" wide that don't have any slots or holes in the areas that will be covered by the suction cup. First available January 2009.